1. Field of the Invention
This invention relates to a calendering roll cleaning apparatus which is employed in a calendering process for smoothing a magnetic layer of a magnetic tape, for example, in the course of the production of a magnetic tape, and a cleaning tape employed in the calendering roll cleaning apparatus.
2. Description of the Prior Art
In a coated type magnetic tape, after application of a magnetic paint on a non-magnetic substrate, a process known as calendering is carried out for smoothing the surface of a magnetic layer of the tape. In the calendering process, the magnetic tape is pinched between an elastic roll and a stainless steel calendering roll maintained at a higher temperature and having its surface machined to a mirror finish. While an increased pressure is maintained between the rolls, the rolls are rotated relative to each other to feed the tape to smooth the surface of the magnetic layer.
However, with the coated type magnetic tape, it may occur that the binder contained in the magnetic paint be dislodged and become affixed to the calendering roll surface. The binder thus affixed to the calendering roll is increased in its bonding strength to the roll and in thickness as time elapses because the calendering roll is maintained at a higher temperature and at an elevated pressure. Should calendering be continued without attending to such condition, the surface of the magnetic layer becomes rough due to the presence of lumps of the binder. As a result, dropout results in the produced magnetic tape and hence satisfactory recording/reproduction can not be achieved.
The conventional practice in removing the foreign substance, such as the binder, thus affixed to the calendering roll surface, has been to use a cleaning tape which is kept in sliding contact with the calendering roll to remove the binder from the roll surface.
However, if only the cleaning tape is slidingly contacted with the calendering roll surface, the binder or the like foreign substance which has become affixed to the calendering roll surface cannot be removed reliably. Hence, it has been necessary to interrupt the calendering operation at an interval of one to two hours to wipe the foreign matter off from the calendering roll surface by a manual operation.
In this manner, in the conventional calendering operation, one is obliged to discontinue the operation to wipe the calendering roll surface manually, so that the operating rate cannot be raised, while the magnetic tape cannot be improved in quality.